Concrete-based materials are used in a variety of applications. For example, concrete-based materials are often used to cover walls or other structures. U.S. Pat. No. 6,046,269, issued Apr. 4, 2000, by Nass et al., teaches a concrete-based compound that is used to create a Fresco-like finish on a wall or other structure. The drying time of certain mixtures taught by this patent can be reduced by the use of propylene glycol and methyl carbitol. In effect, these compounds act as accelerants that speed the drying process.
Other accelerates for concrete-based materials are commercially available. For example, BETTOR MBT, S.A., manufactures and sells an accelerant, which is commercially available as BETTACEL. BETTOR MBT may be contacted through their Internet web site, which is hosted at: www.bettor-mbt.es, or at either of the following physical addresses: Headquarters, BETTOR MBT, S.A., Joiers, s/n, 08184 Palau de Plegamans, (Barcelona), Spain; Telephone: 93 862 00 23; Facsimile: 93 862 00 19; or Production, BETTOR MBT, S.A., Duero, 23, Polígono Ind. Mejorada, 28840 Mejorada del Campo, (Madrid), Spain; Telephone: 91 668 21 56; Facsimile: 91 668 17 75.
The accelerant, BETTACEL, is an aqueous solution made with inorganic salts and halogens. Its main function is to accelerate drying time and hardening of mortar, increasing the mortar resistance in the process. The accelerant may be used even at low temperatures. This accelerant comes in a liquid state, and should be mixed first with part of the water to be used with the mortar, and then added to the mortar as the rest of the water is added. It comes in containers weighing 30 kg or 250 kg. The characteristics of this accelerant are as follows:
Color:Cloudy, non-colorpH:9 ± 1Density:1.3 ± 0.02 g/cm3Chloride ions amount:25.5 ± 1.5%The recommended dosage is 2 to 5% of the weight of the mortar being used. This percentage varies according to the desired effect (how fast you want the mortar to dry), the temperature and the type of cement with which the accelerant will be applied.
Again, concrete-based materials are widely used on buildings or other structures to provide an even exterior surface. The concrete-based materials are spread over a rough concrete surface. Such rough concrete surfaces include bricks, blocks or stones that are held together by a cement.
Concrete-based materials for providing an even exterior surface are widely known, and commonly used in the construction arts. For example, U.S. Pat. No. 4,222,785, issued Sep. 16, 1980, by Henderson, teaches a concrete-based material suitable for application to the exterior of a building. This particular mixture provides certain insulating characteristics.
U.S. Pat. No. 4,229,225, issued Oct. 21, 1980, by Kraszewski et al., teaches another concrete-based material suitable for application to the exterior of a building. This particular mixture includes:                20–60% cement;        30–70% inorganic or organic filler;        2–10% zirconium, hafnium, vanadium or cesium silicate fibers;        0.2–1% plasticizers for cement;        1–3% adhesive; and        0.1–0.5% water-repellent.This above mixture provides certain water-repellent characteristics discussed therein.        
U.S. Pat. No. 4,946,505, issued Aug. 7, 1990, by Jungk, teaches yet another concrete-based material. More specifically, it teaches certain methods of dying concrete-based materials. The dyed materials may be applied to the exterior of a building or other structure.
Each of the above-identified patents are expressly incorporated herein by reference.
Similar one-coat concrete-based materials are also widely available in commercial markets. For example, Lafarge Texsa Morteros and Sermarksa sell many generic one-coat grey or white concrete-based products. Lafarge Texsa Morteros can be contacted at the following physical address: Lafarge Texsa Morteros, Pol. Can Peligrí, C/Ferro, 7-08755, Catellbisbal(Barcelona), Spain; Tel. 936351290. Sermarksa can be contacted at the following physical address: Sermarksa, Carr. 152 Km9, 08110 Monocada, Rey Sak, Barcelona, Spain; Tel. 935726500.
PROPAMSA, S.A., is another company that manufactures and sells a number of concrete-based (or mortar-based) products that may be used to create an even interior or exterior surface on a building or other structure. These include PROPAM REVOC and REVAT RASPADO. PROPAMSA may be contacted at the following physical address: PROPAMSA, S.A., Ctra. N-340 Km 1242.3, Pol. Ind. Les Fallulles, San Vincent Del Horts, 08620 Barcelona, Spain. The application and characteristics of these products are discussed below.
The PROPAM REVOC and REVAT RASPADO products can be used by following a simple three-step process. First, the products are mixed with water to the desired consistency. Second, the products are applied to a rough concrete surface using a smooth trowel 100 (shown in FIG. 1). Third, when the product becomes semi-dry, the exterior skin is removed using a rough trowel 200 (shown in FIG. 2). This creates an even exterior finish that is both attractive and resistant to weather. FIG. 3 shows the application of these concrete-based materials 310 to a block wall 320.
PROPAM REVOC is a mortar based on cement, additives and aggregates that give it the property of high impermeability. It must be applied to a base that is resistant, completely hardened and extremely clean (free of dust, paint, oil, etc.). Also, if the base is exposed to sun or is made of a highly absorbent material, then the surface must first be dampened before applying PROPAM REVOC.
PROPAM REVOC is sold in 25 kg bags that are mixed manually or mechanically with 17% water (about 4.5 L). Once it is mixed it must be applied within 25 minutes or it will begin to harden. This mixture comes in gray and white and will cover approximately 2 kg/m2 per cm of thickness. This, however, depends upon both the flatness and the roughness of the surface. For example, rough brick surfaces will require more, relatively smooth and even concrete walls will require less.
The characteristics of this particular product are as follows:
Apparent density of the powder:1.6g/cm3Mixing water:17%Apparent density of the paste:2.0g/cm3Mixtures lifetime:90minutesDensity of hardened product:1.7g/cm3Flexotraction strength:20kg/cm2Compressive resistance:60kg/cm2Coefficient of capillarity:0.6g/dm2 min1/2Modulus of elasticity:85.000kg/cm2
REVAT RASPADO is a one-coat mortar also based on cement, additives and aggregates that give protection as well as a decorative finish to a building. This product is impermeable to rain water and permeable to water vapor to prevent condensation.
REVAT RASPADO is prepared by mixing the 30 kg bag with 20% water (6 L) until a smooth paste is formed. Once the mixture is made, it must stand for 5 minutes so the mixture will settle. Then the mixture is spread with a trowel. If it is applied to a highly absorbent surface, a first coat should be applied as a primer. The additives include dyes, and the product is available in a variety of colors. It will cover approximately 20 kg/m2 per cm of thickness. The type of finish and lack of flatness of the surface will alter the coverage of this mortar. The characteristics of this particular product are as follows:
Product in powder form:Apparent density:1.4g/cm3Loss in 450° C. fire:1%Loss in 900° C. fire:35%Particles greater than 1.2 mm4.0% (by weight)Particles greater than 0.18 mm55.0% (by weight)Product in paste form:Mixing water:20%Apparent density:1.8g/cm3Hardened product:Product density:1.6g/cm3Flexural strength:35kg/cm2Compressive resistance:80kg/cm2Tensile strength:8.3kg/cm2Elasticity modulus:90,000kg/cm2Shrinkage:1.0mm/mCoefficient of capillarity:1g/dm2 min1/2Permeability to vapor:0.5g/m2 h mmHg
Under typical application conditions (approximately 80 degrees Fahrenheit and high humidity), the expected dry time of PROPAM REVOC or REVAT RASPADO can exceed 4 hours (as long as 6 hours has been observed). As will be appreciated from the foregoing, the application of these products is labor intensive. First, the application requires a significant expenditure of labor hours even for a relatively small area. Then, after the product has set, another significant expenditure of labor hours is required to remove the exterior skin with the rough trowel. Some methods of reducing the required labor hours have been developed. For example, the mortar can be sprayed upon the surface of a building rather than applied manually. This somewhat reduces labor hours, but still requires a significant effort to smooth and remove the exterior skin. The labor-intensive nature of these products is not unique. Other concrete-based materials used to treat the interior and exterior of a building also require a significant expenditure of labor hours.
In addition to labor hours, another important feature of a one-coat mortar is its finish. When the product is finished it must present a smooth attractive surface. Preferably, the surface is flat and even, however, a perfectly flat and even surface lacks a certain desirable aesthetic. Indeed, the cold, hard look of a concrete surface has limited the acceptance of one-coat mortar finishes. Thus, developing a more attractive aesthetic remains an important object of one-coat mortar finishes.